Illumination of tissue can induce endogenous tissue fluorescence, also known as autofluorescence. The spectrum emitted by tissue autofluorescence can be characteristic of a tissue's underlying condition. For example, when illuminated with 370 nm light, the spectrum emitted from normal mucosa differs from that of an adenoma. Tissue autofluorescence spectrometry can thus be employed to diagnose cancerous conditions such as adenoma. Other conditions that can be identified by tissue autofluorescence include arteriosclerosis.
Tissue fluorescence may be based on intrinsic properties of the tissue, or on the differential uptake of a fluorophore administered before the spectrometry is performed.
Interventional tissue autofluorescence spectrometry is known in the art. Currently known devices locate the spectrometer at the proximal end of the interventional device, i.e. outside the patient. These devices rely on fiber optic bundles to transmit light between the analysis site and the externally-located spectrometer. The limitations inherent in employing fiber optic bundles are threefold. First, they are expensive. Second, they are stiff, lacking flexibility and maneuverability. Third, they are large, requiring a relatively large diameter to transmit the necessary amount of light to and from the analysis site. Currently known interventional spectrometry devices are thus limited to use in relatively large and straight passages, such as the gastrointestinal tract.